History and exam
Key diagnostic factors
common
presence of risk factors
Key risk factors include exposure to respiratory syncytial virus (RSV), no recent immunoprophylaxis against RSV, history of prematurity, infants <6 months, chronic lung disease, complex congenital heart disease, immune deficit, winter season, and older age.
exposure to RSV
Respiratory syncytial virus (RSV) has a 98% attack rate for first-time infections and a 75% attack rate for subsequent infections.[44] Transmission requires close contact.
Attendance at day care (nursery), multiple siblings, and birth during the first half of the RSV season are risk factors for more severe RSV disease.[1][45]
infants at high risk for RSV infection
Includes infants <6 months and those with a history of prematurity, chronic lung disease, complex congenital heart disease, and immune deficiency, and neuromuscular disorders, particularly infants in this group with no recent immunoprophylaxis against respiratory syncytial virus (RSV).[1][15][16][46][17][18][83][98]
Down's syndrome appears to be an independent risk factor for hospitalisation with RSV disease.[55][56][57][58]
winter season
Seasonal outbreaks occur worldwide during the winter months.[23]
In the northern hemisphere, epidemics generally begin each November, with a peak in January or February. Cases then decline over the next 2 months with sporadic cases occurring throughout the remainder of the year.
Regional variability also occurs but is less predictable.[23]
In the southern hemisphere, seasonal outbreaks occur from May through September.[23]
older adult age
immune deficiency
There is a higher burden of respiratory syncytial virus (RSV) disease in both adults and children with immune deficiency. Patients who received solid organ or stem cell transplantation as well as those with solid tumours, leukaemia, lymphoma or those receiving chronic immunosuppression are at increased risk of RSV disease.[99]
Among immune deficient patients, the greatest incidence of RSV infection is seen in patients receiving haematopoietic stem cell transplants and lung transplants.[30] Patients with RSV receiving haematopoietic stem cell transplants develop progression from upper to lower respiratory tract infection in 40% to 60% of cases; in these patients, lower respiratory tract infection is associated with mortality rates of up to 80%.[30]
rhinorrhoea/congestion
tachypnoea
Common in moderate to severe infection.[53]
increased work of breathing
cough
May be dry or wet.[2]
wheeze
Results from the combination of mucous plugging and airway narrowing due to inflammation. May range in severity from mild to pronounced. Wheeze or crackles may be found on chest auscultation.[53]
poor feeding
cyanosis
Common in more severe disease.[53]
rales
Evidence of lower respiratory tract infection may be present in 20% to 30% of infants.[8]
uncommon
apnoea
A well-known complication in infants and has been associated with infant death.[84] Incidence may be as high as 20% in infants <6 months of age but is most common in infants aged <1 month.[84][101][102][103][104][105] Respiratory syncytial virus-related apnoea is usually self-limiting and does not recur with subsequent infections.
Other diagnostic factors
Risk factors
strong
exposure to RSV
Respiratory syncytial virus (RSV) has a 98% attack rate for first-time infections and a 75% attack rate for subsequent infections.[44] Transmission requires close contact.
Attendance at day care (nursery), multiple siblings, and birth during the first half of the RSV season, are risk factors for more severe RSV disease.[1][45]
haemodynamically significant congenital heart disease
history of prematurity
immune deficiency
Immune deficiency may be due to chemotherapy for leukemia, immunosuppression after organ transplantation, untreated human immunodeficiency virus, or combined immunodeficiency syndrome. These patients are at increased risk of severe disease, prolonged disease, and prolonged viral shedding.
Among patients with immune deficiency, the greatest risk of clinically severe respiratory syncytial virus (RSV) infection is seen in patients receiving haematopoietic stem cell transplants and lung transplants. Patients with RSV receiving haematopoietic stem cell transplants develop progression from upper to lower respiratory tract infection in 40% to 60% of cases; in these patients, lower respiratory tract infection is associated with mortality rates of up to 80%.[30]
chronic lung disease
Bronchopulmonary dysplasia increases risk for severe disease.[49]
indigenous/American-Indians/Alaska native infants and young children
Aboriginal and Torres Strait Islander infants in Australia have both higher rates of respiratory syncytial virus (RSV)-related hospitalisation and higher rates of RSV mortality than non-indigenous infants.[50] In one US birth cohort study, some of the highest RSV rates were observed in American-Indian/Alaskan native infants.[51]
infants ages <6 months
winter season
Seasonal outbreaks occur worldwide during the winter months.[23]
In the US and throughout the northern hemisphere, epidemics generally begin each November, with a peak in January or February. Cases then decline and end in May. Regional variability also occurs but is less predictable.[23] In the southern hemisphere, seasonal outbreaks occur from May through September.[23]
weak
smoke exposure
family history of asthma
The data are conflicting. Family history of asthma may be a risk factor for severe respiratory syncytial virus disease.[54]
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